1. Field of the Invention
The present invention relates generally to electrochemical sensors which are designed for use in measuring and monitoring electrochemical properties of liquids. More particularly, the present invention relates to an electrochemical sensor which is adapted for use in monitoring liquids using DC and AC voltammetric techniques.
2. Description of Related Art
U.S. Pat. No. 4,631,116, assigned to the present common assignee, discloses a method for monitoring the minor constituents which are present in plating bath solutions which affect plating deposit properties. The method involves applying a predetermined DC potential to a working electrode positioned within the plating bath solution. The DC potential is determined with respect to a reference electrode. A constant AC signal is superimposed on the DC potential. The DC potential is varied at a predetermined rate over a predetermined range which includes potentials which plate and strip the plating deposits.
The AC current of the applied AC signal is measured between the working electrode and a counter-electrode positioned within the plating bath solution as the DC potential is varied over the predetermined range. The measurement of the AC current in relation to varying DC potential is expressed as in AC current spectra or fingerprint. By optimizing all AC and DC measurement variables, spectra are obtained which contain fine structure and which enable the monitoring of minor plating bath constituents which affect plating deposit properties.
In order to conduct the delicate DC and AC voltammetric measurements in accordance with the above procedure, it is important that the three electrodes (reference, working and counter) be shielded from hydrodynamic and electrical interference from the plating bath. Further, it is important that the electrodes be positioned within the sensor apparatus in a manner which allows continuous and uniform passage of plating bath solution into contact with the electrodes. This requirement is necessary to ensure that the plating bath solution to which the electrodes are exposed is an accurate reflection of overall conditions within the plating bath.
In many large scale production facilities, it would be desirable to have a rugged electrochemical sensor which can withstand continual rough treatment while still providing the extremely accurate measurements mentioned above. The sensor should also be easily assembled and disassembled to allow cleaning and inspection. Further, the sensor should be constructed so that different electrodes may be changed into and out of the sensor to allow measurement of a variety of electrochemical properties in many different types of liquids.
As is apparent from the above, there presently is a need for multi-purpose sensor devices which are rugged enough to withstand commercial and industrial scale operations while at the same time providing for continual nonturbulent flow of solution into contact with the sensor electrodes in order to provide accurate electrochemical analysis of a variety of liquids.